org-mode/contrib/babel/library-of-babel.org

#+title:    The Library of Babel
#+author:     Org-mode People
#+STARTUP:  odd hideblocks

* Introduction
  The Library of Babel is an extensible collection of ready-made and
  easily-shortcut-callable source-code blocks for handling common
  tasks.  Org-babel comes pre-populated with the source-code blocks
  located in this file. It is possible to add source-code blocks from
  any org-mode file to the library by calling =(org-babel-lob-ingest
  "path/to/file.org")=.
  
  This file is included in worg mainly less for viewing through the
  web interface, and more for contribution through the worg git
  repository.  If you have code snippets that you think others may
  find useful please add them to this file and [[file:~/src/worg/worg-git.org::contribute-to-worg][contribute them]] to
  worg.
  
  The raw Org-mode text of this file can be downloaded at
  [[repofile:contrib/babel/library-of-babel.org][library-of-babel.org]]

* Simple
A collection of simple utility functions

#+srcname: echo
#+begin_src emacs-lisp :var input="echo'd"
  input
#+end_src

* File I/O
** reading and writing files
Read the contents of the file at =path= into a string.
#+srcname: read
#+begin_src emacs-lisp :var path=""
  (with-temp-filebuffer path
    (buffer-substring (point-min) (point-max)))
#+end_src

Read the lines of the file at =path= into a list.
#+srcname: read-lines
#+begin_src emacs-lisp :var path=""
  (split-string
   (with-temp-filebuffer path
     (buffer-substring (point-min) (point-max))))
#+end_src

Write =data= to a file at =path=.  If =data= is a list, then write it
as a table in traditional Org-mode table syntax.
#+srcname: write
#+begin_src emacs-lisp :var data="" :var path=""
  (with-temp-file path
    (org-babel-insert-result data))
  nil
#+end_src

** remote files

Read local or remote file in [[http://www.json.org/][json]] format into emacs-lisp objects.
#+srcname: json
#+begin_src emacs-lisp :var file='() :var url='()
  (require 'json)
  (cond
   (file
    (with-temp-filebuffer file
      (goto-char (point-min))
      (json-read)))
   (url
    (require 'w3m)
    (with-temp-buffer
      (w3m-retrieve url)
      (goto-char (point-min))
      (json-read))))
#+end_src

* Plotting code

** R
  Plot column 2 (y axis) against column 1 (x axis). Columns 3 and beyond, if present, are ignored.

#+srcname: R-plot(data=R-plot-example-data)
#+begin_src R :session *R*
plot(data)
#+end_src

#+tblname: R-plot-example-data
| 1 |  2 |
| 2 |  4 |
| 3 |  9 |
| 4 | 16 |
| 5 | 25 |

#+lob: R-plot(data=R-plot-example-data)

#+resname: R-plot(data=R-plot-example-data)
: nil

** Gnuplot

* Table/Matrix manipulation

Elegant lisp code for transposing a matrix.

#+tblname: transpose-example
| 1 | 2 | 3 |
| 4 | 5 | 6 |

#+srcname: transpose
#+begin_src emacs-lisp :var table=transpose-example
  (apply #'mapcar* #'list table)
#+end_src

#+resname:
| 1 | 4 |
| 2 | 5 |
| 3 | 6 |

* Misc
#+srcname: python-identity(a=1)
#+begin_src python
a
#+end_src

#+srcname: python-add(a=1, b=2)
#+begin_src python
a + b
#+end_src